JPH0277006A - Camera - Google Patents

Abstract

PURPOSE:To accomplish photographing with high focusing accuracy by providing a conversion control means for actuating a conversion means by using a correction conversion factor obtained by correcting the error of a set conversion factor after starting a release action. CONSTITUTION:The title camera is provided with the conversion control means muC for actuating the conversion means for obtaining driving quantity for focusing by using the set conversion factor and deviation detected by a focus detection means consisting of an optical system for detecting focus AO, a focus detection circuit AFS and a microcomputer muC by using the correction conversion factor obtained by correcting the error of the set conversion factor after starting the release action. Therefore, focusing can be performed with the little shortage of focusing quantity though the detected deviation just before mirror up is used. Besides to that, since a focusing action is performed just before exposure, photographing excellent in follow-up to a moving object and with a good shutter chance can be performed. Thus, a photograph with high focusing accuracy can be taken in an intended timing.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a single-lens reflex camera capable of automatic focus adjustment, and more particularly, to a single-lens reflex camera capable of automatic focusing. a focus detection means for repeatedly detecting the deviation from the focal point; a conversion means for determining a driving amount for focus adjustment using the detected deviation by the focus detection means and a setting conversion coefficient; The present invention relates to a Camilla that is provided with a focus adjusting means for moving a photographing lens toward the focusing position in between.

[Conventional technology]

In the camera described above, the setting conversion coefficient converts the detected deviation into a drive amount for focus adjustment of a drive source such as a motor necessary for moving the photographic lens in order to eliminate the deviation detected by the focus detection means. It differs depending on the transmission system of the drive transmission system from the motor etc. to the photographic lens. Therefore, in single-lens reflex cameras that use various photographic lenses with different focal lengths, etc., each photographic lens has a transmission shaft that receives and takes the driving force from the camera body, to the lens that is finally driven. Generally, a coefficient corresponding to the transmission ratio of the camera is provided as information, and a product obtained by multiplying that coefficient by a coefficient specific to the camera body is used as a setting conversion coefficient.

By the way, the above-mentioned coefficient for each photographic lens is usually a constant value for a single focal length photographing lens, but for a lens whose focal length changes such as a zoom lens, it is different for each focal length with different transmission ratios. It is set. in general,
Changes in focal length are performed by detecting the associated changes in the position of the variator lens using a contact encoder, so it is possible to detect analog changes in focal length step by step and set coefficients for each. Errors due to this cannot be avoided, and it is preferable to vary the conversion rate slightly depending on the open aperture value and the deviation at that time.As a whole, the set conversion coefficient contains an error of about 20%.

Therefore, when moving the photographing lens toward the focus position based on the drive amount determined using such a setting conversion coefficient, for example, when photographing a stationary subject due to the above-mentioned error, If the lens moves beyond the in-focus position, the subsequent automatic focus adjustment operation will cause the taking lens to return to the in-focus position, making the movement of the taking lens jerky and giving a strange feeling. Therefore, it is known that the setting conversion coefficient is set to a relatively small value so that the driving amount is converted so that the photographing lens does not exceed the in-focus position, taking into account the error in the setting conversion coefficient.

The shortfall in the focus adjustment amount for the accurate focus position due to the small setting conversion coefficient is gradually resolved by focus adjustment based on repeated focus detection after the focus adjustment is performed. Eventually, it will converge to the in-focus position.

[Problem to be solved by the invention]

By the way, when performing the automatic focus adjustment operation, if the focus adjustment is continued until just before the start of the shutter operation that actually exposes the film, etc., even if the subject is moving, As a result of being able to adjust the focus according to movement, there is less chance of missing a photo opportunity and it becomes possible to take photos with good focus accuracy. However, in a -eye reflex type camera, when taking a picture, the mirror retraction operation (hereinafter referred to as "mirror up") is required to switch the state in which the light rays from the subject are reflected from the viewfinder optical system to the state in which they reach the photosensitive material such as film. During this operation, the focus detection means cannot receive the beam of light from the subject, so automatic focus adjustment cannot be performed. Therefore, in the conventional camera mentioned above, if the focus is adjusted while the mirror is up using the detected deviation just before the mirror is up, the focus will be The amount of adjustment tends to be insufficient, and in particular, there is a problem in that tracking of moving subjects becomes poor.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a camera that can photograph a moving subject with good tracking ability and higher focus accuracy with less risk of missing a photo opportunity.

[Means to solve the problem]

The characteristic configuration of the camera according to the present invention is such that after the start of the release operation, the conversion means for determining the drive amount for focus adjustment using the detection deviation by the focus detection means and the setting conversion coefficient corrects the error in the setting conversion coefficient. The present invention is based on the provision of a conversion control means that operates using a corrected conversion coefficient.

[For production]

In other words, since the correction conversion coefficient is the one that corrects the error in the setting conversion coefficient, for example, it is necessary to prevent the setting conversion coefficient from overshooting on the premise that it is supplemented by repeated focus adjustment (if it is set to a small value, Even if the above supplement cannot be achieved because the focus detection operation cannot be performed after the start of the release operation, it is possible to compensate for the lack of focus adjustment amount due to the small value of the setting conversion coefficient and move the photographic lens to the in-focus position. Moreover, since no new focus detection is performed after the release operation starts, and no focus adjustment is performed based on the focus detection, even if the photographic lens goes a little too far from the focus position, the photographic lens can be moved again. is not returned to the in-focus position, making operation less likely to cause discomfort.In addition, the smaller the setting conversion coefficient and the larger the open aperture value, the smaller the error in the setting conversion coefficient becomes. Therefore, when the set conversion coefficient is smaller than a predetermined value or when the open aperture value is larger than the predetermined aperture value, the detected deviation is converted into a drive amount using the correction conversion coefficient. With this configuration, even more fine-grained control can be performed.

〔Example〕

Hereinafter, the present invention will be described in detail based on the drawings.

FIG. 1 shows a circuit block diagram of the entire camera.

(μC) is a microcomputer (μC) that performs sequence control of the entire camera and calculations for exposure and focus detection.
(hereinafter referred to as a microcomputer). (LEC) is a lens circuit for a photographic lens that is detachably attached to a camera body (not shown), and transmits information specific to the photographic lens (for example, open F-number, focal length, etc.) to the camera body.

(AFS) is a focus detection circuit that inputs image information obtained by forming an image of light that has passed through the photographing lens through a focus detection optical system (AO) and converts it into an analog electrical signal. This focus detection circuit (AFS) consists of a light receiving circuit (CCD) consisting of a CCD type light receiving element array, a monitoring light receiving element (MC) used for controlling the integration time, and a light receiving element (MC) for monitoring. an integrating circuit (IT) that integrates and outputs the current, a comparator (COM) that compares the output of this integrating circuit (IT) with a predetermined value, and a light receiving circuit (CC).
It is composed of an amplifier circuit (AGC), etc., which amplifies the analog signal from D) according to the output from the integrating circuit (IT).

To briefly explain the operation of this focus detection circuit (AFS), when the microcomputer (μC) outputs an integration start signal (ST), the light receiving circuit (CCD) and the integration circuit (IT) are reset, and each integrates Start. This integrating circuit (I
When the integral output of T) becomes a predetermined value, the comparator (C
When the output of the microcomputer (μC) is inverted, or when the integral timer measured within the microcomputer (μC) reaches a constant value, the microcomputer (μC) outputs an integration end signal (SP).

As a result, the integrated output in the light receiving circuit (CCD) is sent to the transfer register, and then transferred to the microcomputer (μC) via the amplifier circuit (AGC).

The microcomputer (μC) then controls this focus detection circuit (AF
Based on the output from S), the deviation from the in-focus position of the photographing lens with respect to the subject is calculated. That is, a focus detection means is constituted by a focus detection optical system (AO), a focus detection circuit (AFS), and a microcomputer (μC).

On the other hand, the integration circuit (IT) receives the integration end signal (SP).
Input and hold the integral output.

The amplifier circuit (AGC) amplifies the analog signal from the light receiving circuit (CCD) up to eight times according to this output and outputs it to the microcomputer (μC). The microcomputer (μC) has a built-in digital converter (A/D) that converts this analog data into digital data. The above amplifier circuit (
The gain data generated by AGC) is also output to the microcomputer (μC).

(LMC) is a photometry circuit that measures the light that has passed through the photographic lens and detects the brightness of the subject.
v,] is output to the microcomputer (μC). (ISO) is
A film sensitivity reading circuit outputs an apex-based digital signal [Sv] corresponding to the film sensitivity to a microcomputer (μC). (DISP) is a display circuit that displays the focus state of the photographing lens, etc.

(ENC) is an encoder that detects the rotation amount of the focus adjustment motor (hereinafter abbreviated as AF motor) (M),
It is output as a pulse (pulse output for a predetermined amount of rotation of the motor (M)) signal to a lens control circuit (LECON), which will be described later. The lens control circuit (LECON) inputs a motor rotation amount (number) signal and a motor control (speed and direction) signal from a microcomputer (μC), and based on these, drives the AF motor CM), and also drives the AF motor CM). A pulse signal from an encoder (ENC) is input to detect whether or not the AF motor (M) has rotated by a predetermined amount (motor rotation amount), and also performs stop control of the AF motor (M). The microcomputer (μC) has a counter inside to know the lens position, and the encoder (E
The counter performs a count-up or count-down operation in response to input of a pulse signal from an NC.

In other words, a microcomputer (μC) and a lens drive circuit (LEC)
ON) and the AF motor (M) constitute a focus adjustment means that moves the photographing lens to a focus position for the subject based on the detected deviation by the focus detection means.

(ASL) is an auxiliary light circuit that emits auxiliary light toward the subject when focus cannot be detected and it is dark. (CD) uses the card circuit of an IC card (not shown) to transfer switch switching information from the outer door from the memory inside the card to a microcomputer (μC).
). For example, the switch switching information may include whether only one-shot AF (eye movement focus adjustment state in which the lens is not driven after focusing) or only spot AF (focus detection state using a narrow area) is possible. Auxiliary light AF (
Focus detection by emitting the auxiliary light is prohibited.

(BAT) is a power supply battery that supplies power to all circuits.

(SM) is activated by operating the main switch (not shown).
It is a switch that is opened and closed. (Sl) is a photometry switch that is closed by pressing the first step of the release button (not shown). Closing this photometry switch (Sl) performs photometry operation and automatic focus adjustment operation. be exposed. (S
2) is a release switch that is closed by a second pressing operation subsequent to the first pressing operation on the release button, and by closing this release switch (S2),
A photographing operation is performed. (Ss/w) is Suzutto AF (
Focus detection state using only the narrow center of the three focus detection areas (described later) and Wide AF (described later in 3)
(Focus detection state using all three focus detection areas)
This is the AF area changeover switch.

(E”FROM) is a memory IC built into the microcontroller (μC) or externally attached.
C (82FROM) is an electrically erasable memory that retains its contents even without power supply. This memory IC (E''FROM) can store camera adjustment data, camera mode switching data, and the like.

This allows you to easily set the camera specifications to match the level and needs of the photographer.

Next, the focus detection optical system (AO
) is shown in FIG. 2.

In Figure 2, (TL I ) and (TLz ) are lenses that constitute the photographing lens, and both of these lenses (TL
I).

(T1.) are the distances (PZI), (PZri, (PZI)
<PZ position (hereinafter, this distance is referred to as injection distance)
It is set in. A field mask (FM) is disposed near the predetermined imaging plane (FP). This field mask (FM) has a horizontally long first rectangular opening (EO) in its center, and a pair of vertically long second rectangular openings (Eot) and third rectangular openings (Eo) on both sides. □) is provided. Each rectangular opening (Eo) of the above field mask (FM)
, (Eot), and (EO2), each of which passes through a separate condenser lens (Lo).

(LOl), (Lo□) (Hereinafter, corresponding to the rectangular openings (Eo), (Eot), (EO2) of the field mask (FM), the first condenser lens (LO) and the second condenser lens (Lol ), 3rd condenser lens (Lo□)
It is called. ), respectively, and are focused.

The above-mentioned condenser lenses (Lo), (Lo□), (
Behind Lo□), an aperture mask (AM) and a re-imaging lens plate (L) are arranged. The re-imaging lens plate (L
) is a pair of re-imaging lenses (L
, ), (1,), and pairs of re-imaging lenses (La), (L4) and (La), (Ls) arranged vertically on both sides. The re-imaging lenses (Ll) to (Ll) are all plano-convex lenses with the same radius of curvature. (Hereinafter, the field mask (F
Corresponding to the rectangular openings (Eo), (Eot), (EO2) of Lens pair (La).

(L, ), (La), and (Ll) are respectively referred to as a second re-imaging lens pair and a third re-imaging lens pair. )Also,
The aperture mask (AM) includes each of the re-imaging lenses (L
The diaphragm opening (A1) is located at the position corresponding to l) to (Ll).
- (80) are provided. This aperture mask (AM) is disposed just in front of the re-imaging lens plate (L), and is in close contact with the flat portion of the re-imaging lens plate (L).

Further behind the re-imaging lens plate (L), there are three C
CD line sensor (Po), (POI), (PO2
) is provided. The central CCD line sensor (Po) is arranged horizontally in the center of the board (P), and the CCD line sensors (POI) on both sides
), (PO2) are arranged vertically on both sides of the substrate (P), and are aligned with the installation direction of each re-imaging lens pair on the re-imaging lens plate (L) and each CCD line sensor (PO2).
), (Pop), (Po:> are arranged so that the installation direction is the same as that of the CCD line sensor (
Po), (Pop), and (Po□) are the first . It has two second rows of light-receiving elements, and is configured to separately photoelectrically convert two images re-imaged on the CCD line sensor by the re-imaging lens pair.

(Hereinafter, each of the above CCD line sensors (Po), (Po
t), (PO2), the rectangular opening (Eo), (Eo□) of the field mask (FM).

(EO2), the first CCD line sensor (PO2)
) A second CCD line sensor (Pol) and a third CCD line sensor (PO2). ) The blocks (AFMO) surrounded by dotted lines in the figure are assembled together to form an AF (autofocus) sensor module. And the field mask (FM
)・Condenser lens (Lo), (Log).

(Log)・Aperture mask (AM)・Reimaging lens plate (L
) constitutes a focus detection optical system (AO).

The focus detection device (X) is configured to detect the focus position in the following manner using an image obtained by the focus detection optical system (AQ) configured as described above.

The optical axis (
A beam of light for optical axis distance measurement from a subject in an area outside Op) is incident on the field mask (FM) so as to be separated from the optical axis (Op) at a predetermined angle with respect to the optical axis (Op). The light passes through the second rectangular opening (Eo + ) and enters the second condenser lens (Lo + ). This light beam for the outside of the front axis is bent and focused toward the optical axis (Op) by the second condenser lens (Log), and the second aperture aperture (A3) of the aperture mask (AM), (
A4) and enters the second re-imaging lens pair (La), (L4) of the re-imaging lens plate (L). The optical axis distance measuring light beam incident on the second re-imaging lens pair (La), (L4) is transferred to the second CCD line sensor ( A pair of images are re-imaged in the vertical direction on this second CCD line sensor (Pop).

Similarly, the optical axis distance measuring ray bundle including the chief rays (ls) and (zs) enters the field mask (FM) so as to be separated from the optical axis (Op) at the above-mentioned predetermined angle. 3 rectangular apertures (Eoz), a third condenser lens (Log), and a third aperture aperture (As) of the aperture mask (AM').

(A6) and third re-imaging lens pair (Ls), (Ls)
The light is then focused onto the third CCD line sensor (Pot), and a pair of images are re-formed in the vertical direction on this third CCD line sensor (PO2).

On the other hand, the light beam for off-axis measurement from the subject in the area including the principal rays (i' +) and (j' 2) and the optical axis (Op) of the photographing lens is the light of the field mask (FM). Axis (Op)
The upper first rectangular opening (Eo), the first condenser lens (
Lo), the first aperture aperture (AI), (A2) on the optical axis (Op) of the aperture mask (AM), and the first re-imaging lens pair (Ll), (Lx), the first COD The light is focused onto the line sensor (Po), and a pair of images are re-imaged in the left and right direction on this first CCD line sensor (Po).

Then, the CCD line sensor (Po), (Fo
r).

By determining the positions of the three pairs of re-imaged images formed on the (Pot), the focal position of the photographing lens (2) with respect to the subject is detected.

To explain in correspondence with the viewfinder field diagram shown in Fig. 3, the first CCD line sensor (Po) is located in the on-axis focus detection area (ISI), and the second CCD line sensor (Pop) is located in the on-axis focus detection area (ISI).
is the third CCD in the optical axis focus detection area (IS2) on the right side.
The line sensor (PO2) is located on the left optical axis focus detection area (
IS3). Then, the shooting screen (
Three focus detection areas (ISI) shown by solid lines in the center of the screen for S).

(IS2), (IS3) (hereinafter, when it is necessary to distinguish between them, they will be referred to as the first island (ISI),
2nd island (IS2), 3rd island (JS3)
The camera is configured so that focus detection can be performed on a subject located at In the figure, a rectangular frame (AP) indicated by a dotted line is displayed to indicate to the photographer the photographing area in which focus detection is being performed. In addition, the display section shown outside the shooting screen (S) (
Dfa) indicates the focus detection state, and lights up in green when in focus, and lights up in red when focus cannot be detected. (Dfb) is an LCD for displaying a moving object when a moving object is detected.

Next, the sea fence of camera operation will be explained using the flowchart of FIG.

This flow starts when the main switch (SM) is turned on. First, press the photometry switch (S) with <#400>.
l) is closed, and the photometric switch (S
l) is closed <#400. #405> is looped. In <#405>, it is determined whether the main switch (SM) is opened, and if the main switch (SM) is opened, the microcomputer (μC) enters the stop mode.

If it is determined in <#400> that the photometry switch (St) is closed, lens data unique to the photographing lens is input from the lens circuit (LBC) in <#410>.

This lens data includes focal length data [fl, conversion coefficient [K] between defocus amount and lens drive amount, and open F value (Av value) [Avo] of the photographic lens.

In <#415>, input the film ISO setting data [Sv] from the film sensitivity reading circuit (ISO), and
20>, a photometric operation is performed and photometric data [By] is input from the photometric circuit (LMC). At <#425>, a subroutine (AP) for performing an automatic focus adjustment operation is called, the details of which will be described later. Exposure calculation is performed in <#430>, and the shutter speed [Tv] and aperture value [Av] for which exposure should be controlled are determined.
] is calculated.

Next, it is determined in <#435> whether the release switch (S2) is closed, and if it is closed, <#44
0>, a release permission flag, which will be described later, is used to determine release permission. If the release is permitted, proceed to <#450> and release time lag - release switch (S2
), a subroutine (LNS) is called to calculate the drive amount of the photographic lens and control the lens drive in order to compensate for the shift in focus that occurs during the time delay between the closing of .

If the release switch (S2) is not closed in <1435>, and if the release is not permitted in <#440>, it is determined in <#445> whether the photometry switch (S1) is in the open state, and it is opened. If it is in the closed state, go to <#400>, and if it is closed, go to <1410> for the next photometry/distance measurement.

On the other hand, after performing focus compensation with <#450>,
430>, the shutter speed [Tv] and aperture value [
A subrune (exposure control) that performs exposure control based on [Av] is called at <#455>, the details of which will be described later.

After that, the film is advanced by one frame in <#460>, and it is determined in <#465> whether the photometry switch (Sl) is in the open state, and if it is, the film is advanced in <#40>.
0>Help.

Figure 5 shows the subroutine (
AF>> shows a general flow.

When this subroutine is called, first, <1500
Integration is performed by the light receiving circuit (CCD) of the focus detection circuit (AFS) at >, and the pixel data is AD converted and input at <#502>. Using this pixel data <#504>
Find the amount of focus shift (defocus amount). Also, <
In #502>, card information from the card circuit (CD) is also input, and Continuous AF (
(Automatic focus adjustment state where the lens is driven even after focusing) or
It can also be seen that one-shot AF (an automatic focus adjustment state in which the lens is not driven after focusing) has been set. In other words, I.C.
To force one-shot AF from the card (
Forced one-shot flags (hereinafter referred to as card one-shots) and continuous flags are sent.

In <1506>, the (moving object mode) is determined, which will be explained later, but when it is determined that the subject is a moving object, the moving object mode flag is set.
This is because in the subsequent loop, if the subject is a moving object based on the determination of this flag, the process branches to the moving object processing flow from <#544>. During distance measurement in the first loop, it is not possible to determine whether the subject is a moving object, so be sure to
1508>. Here, it is determined whether continuous AF is used.

The I input in <#502> is continuous.
Continuous AF was forcibly set using the card information from the C card, or <#55 (described later)
2> is either due to the continuous flag being set.

Next, in <#510>, it is determined whether or not focus has been achieved using an after-focus flag, which will be described later. This is after focusing <#524
This is to branch to the flow of moving object determination from >. <
In #512>, it is determined whether the lens is being driven. Then, if the lens is being driven, the next focus determination and moving object determination will be performed with poor precision, so they are skipped. <#514>
Now, it is determined whether the photographing lens is within the in-focus zone. If it is within the focus zone, set the after-focus flag (used in <#510>) with <#520>, and <#522>
> to display the focus (line display on the display section (Dfa) shown in Fig. 3) and release permission flag (Fig. 4 <144).
0>).

On the other hand, if it is not within the focus zone in <#514>, <#5
16>, determine whether the lens is driven 3 times or more, and
If the amount of defocus is greater than or equal to the amount of defocus, the moving object is determined using the past three defocus amounts in <#518>. If it is determined in <#518> that the object is not a moving object, and if it is determined in <#516> that it has not been driven three or more times, the lens for focus adjustment is driven in <#540> and the main routine returns. return to,
Loop to the next distance measurement from <#500>.

If it is determined in <#510> that the after-focus flag is set, the process proceeds to <#524>, where it is determined whether distance measurement has been repeated four times, and if distance measurement has not been repeated four times consecutively, the process proceeds to <#524>. Return to the main routine and loop to the next distance measurement from <#500>.

When the four distance measurements are completed, in <#526>, the four defocus amounts that are the results of these four distance measurements are averaged to obtain the average defocus amount [DFx]3, and in <#528>
Then, it is determined whether or not the subject is moving away using the past two average defocus amounts [DFx]. If the subject is moving away, the process proceeds to <#542> and sets an AF lock flag.

Note that in the first loop, the two average decoupling forces [D
Since there is no data for [Fx], use the same value.

If the subject is not far away in <#528>, <#5
30>, it is determined whether the average defocus amount [DFx] has reached four or more. This is the following <#53
In the moving object determination of 2>, this average defocus amount [DFx
] is the method that makes a determination only when all four are present. If the average defocus amount [DFx] is not equal to four, the process returns to the main routine and the next
#500〉From the distance measurement loop.

If you have four average defocus amounts [DFX], <#53
2>, a moving object is determined using the four average defocus amounts [DFx]. If it is determined that the object is a moving object in <#532>, the process proceeds to <#534>. Also, if it is determined that the object is a moving object in <#518>, the process proceeds to <#534>.

In other words, there are two ways to determine that a subject is a moving object: If the subject is moving at a relatively fast speed, <#518> is used; on the other hand, if the subject is moving at a relatively slow speed, the
#532>, each object is determined to be a moving object.<#
534>.

Hereinafter, these will be referred to as "moving object determination type I" and "moving object determination type ■." Then, if it is determined to be a moving object, <#
Set the moving object mode flag (used in <#506>) in <#534>, calculate the moving object correction in <#536>, and add the predicted amount of defocus that will occur due to the moving object to the normal amount of defocus. to find the lens drive amount.

Thereafter, <#538) is used to display a moving object (as shown in FIG. 3).

Display of L CD (Dfb)) and drive the lens with <#540>. Hereinafter, the operation mode in which the above-mentioned moving object correction and lens driving are performed will be referred to as (moving object mode).

After entering (moving object mode) in this way, after driving the lens,
The program returns to the main routine and loops back to <#500>. This time, proceed from <#506> to <#544> to calculate the moving object correction.

However, the moving object correction calculation of this <#544> is
＞Unlike the moving object correction calculation for lens drive, ＜#53
In 6>, correction is performed with the goal of completing the next distance measurement, whereas correction is performed with the goal of completing the current distance measurement.

In <#546>, focus is determined based on the corrected value, and if in focus, in-focus display and release permission are performed in <#548>. Subsequently, in <#550), it is determined whether the direction of movement of the subject has been reversed during (moving object mode).

If it is reversed, set the continuous flag (continuous mode) with <1552>, and press <#
554> to clear the moving object mode.

In other words, if correction is performed even though the moving direction of the subject is reversed, there will be a time delay due to the integration time of the CCD line sensor when detecting the movement of the subject, and there will be a delay in the motion correction itself. This is because continuous AF is better at tracking subjects that move randomly back and forth. It is.

Figure 6 shows “moving object detection type I” and “moving object detection type ■”
This is a sea fence diagram. A relatively fast-moving subject, i.e. approximately 1.3m in film surface terms.
[m/s] or more can be detected as "moving object determination type I."

1. Drive the lens with the second distance measurement <A> and <8>,
After focus confirmation distance measurement <C>, moving object detection begins. The reason for this is that in the distance measurements of <A> and <B>, backlash from lens drive is included, or the focus detection accuracy is low due to a large distance from the in-focus position, or the amount of defocus This is because in many cases, the distance measurement of <B> does not yet enter the in-focus zone due to errors in the conversion coefficient [K] of the lens drive amount. And then in a stationary state.

If it is a certain subject, there are few causes of error such as those mentioned above <C
The fact that the distance measurement <C> should result in focus, but the distance measurement <C> does not result in focus means that the subject is a moving object. Therefore, after driving the lens based on the distance measurement result of <C>, the distance measurement of <D> is also out of focus and <
If the camera is out of focus even after distance measurement with E>, the camera enters (moving object mode) for the first time. Then, the moving object is corrected using the detected defocus amounts obtained in the three distance measurements <C>, <D>, and <E>. In other words, the moving object speed is calculated by averaging two speeds: the speed calculation using the detected defocus amount by <C> and <D>, and the speed calculation using the detected defocus amount by <D> and <E>. That's what I do.

Until distance measurement <C>, the focusing zone is a narrow zone of [80 μm]. This is based on the assumption that the subject is stationary, and is a size that guarantees focus within this zone. Once within this zone, there is no need to drive the lens thereafter. After the distance measurement of <D>, the focusing zone is set to [2].
00 μm]. This is based on the assumption that the subject is moving, and if the subject moves more than [200μm] in the lens drive cycle based on the results of one distance measurement, it is determined by the "moving object measurement type" and the operation mode is set (moving object measurement type). mode).

When the object is in focus with respect to the [200 μm] focusing zone, moving object detection thereafter shifts to detection using "moving object detection type (■)". In addition, if an interrupt occurs due to the closing of the release switch (S2) before shifting to "Moving object detection type ■", the drive for the photographing lens during release (Fig. 4<#
450> ). Furthermore, when the focus is achieved by distance measurement of <C>, the moving object is detected as "moving object detection type (■)".

In "Moving Object Detection Type ■", after focus is achieved with confirmation distance measurement <C>, distance measurement is repeated four times in a row with the photographic lens stopped. As shown in Figure 6 (b), <Di>
, <02>, <D3>, and <04> were carried out four times in a row, and the defocus amounts obtained in each distance measurement were averaged to obtain the average defocus amount CDFX.
Repeat distance measurement one time at a time. And <El> ~ <E4>
, <Fl>~<F4>.

When the average defocus amount [DFx] is determined in each of the four distance measurements from <G1> to <64>, a moving object determination is performed using these four average defocus amounts [DFx]. The speed of the object that can be detected with this "moving object detection type (-)" is at least [0.25 mm/s] in terms of film surface. If the subject is detected to be a moving object with this "moving object detection type (■)", the operation mode enters (moving object mode), and moving object correction and moving object display are performed.

FIGS. 7 and 8 specifically show the flow of moving object detection using "moving object detection type I" and "moving object detection type ■". Corresponding to the flowchart in Figure 5 above, <#5
16> and <#518> are based on "moving object detection type I", and <#524> to <#532> are based on "moving object detection type ■".

In the “motion detection type ■” shown in Figure 7, first <#71
0>, it is determined whether [LCNT] is "3" or more.

[LCNT] is a drive counter that counts the number of lens drives <9540>. By clearing this drive counter when the photometry switch (Sl) is closed, this drive counter is incremented each time <#750> is passed, and is used as a counter for entering moving object determination. Check the driving counter in <#710>, and if the lens is driven for the third time or more, <#7
15> to find the subject speed (<C> and < in Figure 6)
D> distance measurement). Next, if the drive counter is '3' in <#720>, go to <1750>. If the drive counter is '4' in <#720> (distance measurement of <D> and <E> in Figure 6), there is no moving object. Make a judgment.

Next, each condition for moving object determination is checked. In other words, using the auxiliary light circuit (ASL) in <#725> (
(auxiliary light AF mode). <#73
0>, it is determined that the subject is not dark. It is determined that the image is not dark if the gain of the amplifier circuit (AGC) in the focus detection circuit (AFS) is less than 4 times. <
1735>, it is determined that the subject magnification is not high. This is because when the magnification is high, the variation in distance measurement is large and the detection error is large. And in <#745>, <#7
15> The two past subject speeds (obtained from the distance measurement results of <C> and <0> in Figure 6, and from the distance measurement results of <D> and <E>) objects) are in the same direction. Then, when each of the above-mentioned conditions is satisfied, in <#745>, the past two subject speeds are averaged to obtain the subject speed to be used in <#534> and below.

Here, in order to perform the moving object detection using this "moving object detection type ■", there is another condition that it does not enter the in-focus zone, but the detailed flow of this in-focus zone judgment performed in <#514> will be explained using FIG.

In this flow, first check the drive counter with <#910>, and if it is greater than or equal to "3", set the focusing zone to [200 μm] with <#920>, and if it is less than "3", set the focusing zone with <#930>. > to set the focusing zone to [80 μm].
80μm], <D>, <E> [200μm]
]). Therefore, in continuous AF, the focus zone is usually [200 μm]. And <
Defocus amount [Kane] which is the distance measurement result in #940> and <
The focus zone is compared with the focus zone set in #920> or <#930>, and if in focus, proceed to <#520>; if out of focus, proceed to <#516>.

FIG. 8 shows "moving object determination type (■)". first,
It is assumed that the defocus amount [sum memory [DF (sum)] is cleared by closing the photometry switch (Sl).

As a result of the determination in <#510>, the flow after focusing (
<#524>~), <1800> displays the defocus amount [DF (current)] and [DF (sum)] obtained in the current distance measurement.
] and save to [DF (sum)]. <#805
> Then, determine whether distance measurement has been performed four times in a row, and if distance measurement has not been performed four times, proceed to <#807> and count up the first determination counter [m]. , return to the main routine (<#590>).

Next, in <6810>, a second determination counter [j2] that determines how many times the four consecutive distance measurements have been performed is counted up. Note that both these counters [1] and [m
] is assumed to be cleared when the photometry switch (Sl) is closed. Further, in <#815>, only the first determination counter [m] is cleared.

<#820> calculates the sum of the four defocus amounts [DF(
Divide the sum) by 4 to find the average defocus amount [DF (flat). In <#825>, it will be described later whether the first value of this average defocus amount [DF (flat)] after focusing (hereinafter referred to as the base defocus amount) [DF,] is stored in memory. Determine using memory flag. If the base defocus amount [DF,] is in the memory, proceed to <#840>, otherwise go to <#830> to convert the first average defocus amount [DF (average)] to the base defocus amount [DFO]. Set as <#83
5> sets the memory flag (used in <#825>).

In <#840>, the average defocus amount [DF (average)] obtained in <#820> is stored in the memory [DF4], and the four memories [DF,], [DF3] are stored.
.

Shift the data in [DF2] and [DFl] in order.

Therefore, the latest average defocus amount [DF (flat)] is always stored in the memory [OF,].

In <#845>, <#850>, and <#855>, determination is made to escape from the moving object determination state and perform AF lock.

First, if the subject is determined to be dark in <, #845>, that is, if the amplification circuit (AG) of the focus detection circuit (AFS)
When the gain of C') is determined to be 4 times or 8 times,
In addition, when the magnification is larger than [1/15] at which the distance measurement calculation results vary in <#850>,
855>, the latest average defocus amount [DF, ] and base defocus amount [DF, ] are compared and if they change by more than [300 μm] toward the distance, both <#8
65> sets the AF flock flag and returns to the main routine (<#590>).

If the AF flock flag is not set, <#86
0>, if it is determined that the latest average defocus amount [DF, ] has moved toward the object by more than [400 μm], the object speed [V] is changed to ( Set it to 0.25 mm/s, which is the minimum speed for maintaining the moving object mode.<#534>
Proceed to.

On the other hand, in other cases, the focal length of the photographing lens is determined in <#864> and <#866>, and the moving object determination level from <#875> is switched. If it is determined in <#864> that the focal length [fl is smaller than [50mm], the determination level [Cnl] is set to [100μm] in <#867>.
Then, with <#866>, the focal length [fl is [200mm]
If it is determined that it is smaller, in <#868> the determination level [Cnl is set to [150 μm] and the focal length [fl is set to [20 μm].
If it is determined that it exceeds 0mm, the determination level [Cn is set to [200um] in <#869>. This judgment level [Cnl is the average defocus amount [
DF (flat)] is used to determine the difference between two values.

Note that the switching of the moving object determination level [Cnl executed in <#864> to <#869> can also be performed by another method. An example thereof is shown in FIG. In this example, the moving object detection level [Cnl] is changed to the focal length [fl corresponding to the defocus amount on the film] and the photographing magnification [
β] and [f·β] as the criterion for determination.

In other words, as a result of the determination in <#864'> and <#866'>, if the product [[・β] is smaller than "5", the moving object determination level [Cnl is set to [100 μm:]<#867
°〉, if the product [f・β] is more than '5'' and less than 20'', the moving object detection level [Cnl is set to [150 μm]<#8
68'>, if the product [f・βco is "20" or more, set the moving object determination level [Cnl to [200 μm]<#869'>
, after setting each, proceed to <#870>.

<#870> How many times has four consecutive distance measurements been made?
In other words, it is determined whether the average defocus amount [DF (flat)] obtained every four consecutive distance measurements is 4, and if it is 4 or more, the moving object from <#875> is determined. Make a judgment. This moving object determination is based on [DF3-DF', ≧Cn and [DF, -DF2≧Cn and [DF4-DF, ≧1.
It is determined that the object is a moving object if all three conditions of 5.Cnl are satisfied. Here, the reason why the determination level is [1,5·Cnl for the last condition is that the span is L5 times that in other cases.

Next, in <#895>, calculate the two average defocus amounts [DF
3] Find the subject speed [v1] using [DF,] and the time between these two distance measurements, and similarly calculate the two average defocus amounts [tl, cnF2] in <#897>.
] and the time between these two distance measurements to find the subject speed [■2], <#899> those two subject speeds [Vl.

After calculating the average speed of [■2] (V・(Vl +V2.)/2) and calculating the average subject speed [Vl, <#534
Go to >.

Below, in the moving object correction, the average subject speed CV] is used to predict the amount of defocus at the end of the next distance measurement.
The focus adjustment operation is repeated by calculating the lens drive amount in addition to this amount. When the image is focused, a release operation is performed. In the release operation, the release switch (S2) may be closed after focusing, or the release switch (S2) may be closed before focusing. Exposure control is performed by closing the 1-noise switch (S2), but during exposure control, the focus detection optical system (AO)
It is constructed in such a way that no light can enter.

To explain moving object correction using Figure 1O, film (F
) is a photographic lens (TL
), the ray flux passes through the finder optical system (F
l) an anti-transmissive main mirror (MM) for reflection;
It passes through the total reflection sub-mirror (SM) and reaches the focus detection optical system (AO). , a focus shift occurs during this mirror up.In order to correct the focus shift during this release time lag (hereinafter, this operation will be referred to as bin 1 ~ compensation),
The shortfall in the amount of movement of the photographing lens during the release time lag is compensated for by driving the lens while the mirror is up (hereinafter referred to as mirror-up driving). In the diagram,
The out-of-focus distance (DF) of the subject is corrected by the mirror-up drive described above.

FIGS. 11 to 13 show driving during mirror up for focus compensation. The horizontal axis is time, and the vertical axis is an axis related to the position of the image plane.

Figure 11 shows the case of "moving object detection type ■", where <X> represents the integration timing, <y> represents the calculation timing, and (
The curve 0) represents the movement of the subject, and the straight line (L) represents the movement of the photographic lens. The speed of the objects shown in FIG. 11 is quite slow, and the objects shown in FIG. 11 also include objects that have started moving from a stopped state.

As a result of distance measurement <C>, the camera is in focus, and the following four consecutive distance measurements <D>, <E>, <F>, and <G> determine that the subject is a moving object, and the timing of <T> Enter (moving object mode). When entering (moving object mode), each calculation end point <1++>, <1+□>.

<tls>, <t+<>, the defocus amount is “0”
Control the movement of the photographic lens so that For example, if an interruption occurs due to closing of the release switch (S2) between timing <t+s> and timing <1+*>, mirror-up will start at the next focusing timing <b+>. Then, the amount of defocus that deviates during mirror up is corrected by driving during mirror up, and at exposure timing <S>, the photographing lens is moved so that the amount of defocus becomes "0".

Figure 12 shows the case of "Moving object detection type ■", in which the photometry switch (Sl) and release switch (Sl) are used from the beginning.
2) is a closed state. Note that the closing of the release switch (S2) is the same operation as shown in the figure, regardless of the timing, until distance measurement of <F> begins. When using “Moving Object Detection Type■”, when shooting a fast-moving subject, distance measurement is less than
A> to <E> are not in focus. Therefore, as explained in FIG. 6, the camera enters (moving object mode) at timing <T> after driving the lens four times, focuses on distance at <F>, and performs a release operation.

In this case as well, driving is performed during mirror up, and the photographing lens is moved so that the defocus amount becomes "0" at exposure timing <S>.

FIG. 13 shows a case in which the same subject as in FIG. 12 is brought into focus at distance measurement <D>, which begins to widen the in-focus zone. In this case, (moving object mode) cannot be entered.

However, considering the range of [200 μm] in the widened focusing zone, a deviation of at least [200 μm] will occur during exposure. Therefore, in order to compensate for this focus shift, <
The amount of defocus (the amount of defocus up to P) determined by the distance measurement of D> is corrected by driving while the mirror is up.

This method makes it possible to eliminate release lag due to out-of-focus without missing a photo opportunity, even if the subject is too small to enter (moving object mode). That is, although the camera is released with the focal zone widened, the out-of-focus caused by widening the focal zone is reduced by driving the lens while the mirror is up.

Table 1 on the next page summarizes this drive during mirror up.

Mirror-up drive does not always occur, but can be switched depending on the autofocus mode.

If you want to fix the focusing because the photographer intended to shake the camera (<#855>), or if the accuracy of motion detection seems to be low, such as when the subject is dark or the magnification is high (<#845> , <#850> ), for slow moving subjects that do not require (moving object mode) (
<9855>) Both are AF locked. During this AF lock, driving while the mirror is up will result in a poor photograph, so do not drive while the mirror is up.

On the other hand, when a moving object approaches or moves quickly, the camera enters the (moving object mode) as described above, so the mirror is driven while it is up, and moving object correction is calculated to ensure that it is in focus at the time of exposure. However, since the mirror-up time is a finite time of about 70 m5, there is a limit to the amount of drive during the mirror-up. The amount of time that can be driven during this [70m51] is less than normal full drive because the photographing lens needs to be stopped during actual exposure, so it is driven while braking. The pulse count is [40 pulses].

If this value is a shooting lens with a longer focal length than a standard lens [50/1.7], the lens will move more than [200μm], so if the shooting lens is stopped at the edge of the focusing zone [200μm]. Only this value can drive the lens.

If the required lens drive amount exceeds this [40 pulses], the start of mirror up is delayed by [40m5l] and the lens is driven during this time. We also put a limit on the amount of lens drive before the release, so as not to lengthen the release time lag (only an increase of [40m5]).
Unlike the drive during mirror up, full drive is possible, so the drive amount is secured for [70 pulses], making a total of [110 pulses].
This makes it possible to drive the lens accordingly. This results in
If the conversion coefficient [K] between the defocus amount and the lens drive amount is small, a lens movement amount of [2000 μm] can be secured, and even if the front-rear conversion coefficient [K] is large, it is possible to secure a lens movement amount of [100 μm].
Since it is possible to secure a certain amount of lens movement, this value can be said to be sufficient for focus correction.

Next, in the case of non-moving object mode, in this mode,
If the release switch (S2) is closed before focusing and the subject is moving at a fairly slow speed, you can immediately perform the release operation without entering (moving object mode). (See Figure 13). In this case and in the case of continuous AF, driving is performed during mirror up without performing moving object correction (unnecessary in the method of this embodiment). The amount of drive at this time is calculated from the distance measurement results just before the mirror is raised. On the other hand, in the case of a stationary subject or a slow-moving subject, the moving object determination is repeated after focusing.

During this time, if an interruption occurs due to opening of the release switch (S2), the mirror is driven while the mirror is up without moving object correction. At this time, it is impossible to determine whether the photographer is trying to photograph a stationary subject or a slow-moving subject.

For example, if you want to lock the AF, if you drive the mirror while it is up, the result will be an unintended photograph.

Therefore, if the subject is in the in-focus zone, the drive will not be performed while the mirror is up, and if the camera has been shaken, the drive will not be performed while the mirror is up. Since it is slow, I assumed that it would be slow and moved the photographic lens slightly by driving while the mirror was up.3.
As a control method that satisfies two phenomena, the amount of defocus [
70 to 200 μm], a method is adopted in which driving is performed during mirror up. In other words, the defocus amount is [
If the amount of defocus is less than [70μm], it is within the focus zone, and if the amount of defocus is more than [200μm], the camera will be shaken,
If the defocus amount is [70 to 200 μm], it is determined that there is movement of the subject.

Next, the driving amount will be explained with reference to FIG. 14.

Since focus was achieved during distance measurement <C>, considering the dispersion in distance measurement, distance measurement <D>, which is averaged, is more accurate. Therefore, during mirror-up driving during moving object determination, the driving amount is determined based on the average defocus amount. First, if the release switch (S2) is closed before entering (moving object mode) assuming that the subject is moving, then the amount of defocus (in Fig. 14) determined from the latest distance measurement results is It is preferable to drive the mirror while the mirror is up using the average defocus amount (DFi) obtained from the distance measurement results in <■> (line (i) in FIG. 14). Also, assuming that the subject is still, the point of focus can be seen in the viewfinder, so the amount of defocus (<D in Figure 14) determined from the distance measurement results immediately after focus is
＞Average defocus amount determined from the distance measurement results＞
It is better to use [DFd] to drive while the mirror is up (
(line (ii) in FIG. 14). Furthermore, if you lock the AF and shake the camera slightly (a camera shake that cannot be detected with <#855>), the measurement will be performed after [about 0.8 seconds] have passed after confirming focus. Defocus amount determined from the distance result (<C> in Fig. 14)
The average amount of defust debris [DF
g] ) to drive the mirror during mirror up (line (ii) in FIG. 14).

Note that the word "premise" here means a camera that emphasizes this. In other words, it is possible to set in advance which distance measurement result to use to drive the mirror while it is up, depending on the intended user of the camera.

For even more detailed control, it is possible to switch which distance measurement result to use to drive the mirror while it is up, depending on the time from focusing to closing the release switch (S2). preferable. As mentioned earlier, the time it takes to shake the camera after focusing is [0
, 8 seconds to [1 second], the timing of <t41> in Fig. 14 will be reached by the distance measurement of <G>, which is performed at the timing of [0.8 seconds] after focusing. When an interrupt is generated by closing the release switch (S2), the mirror is driven up using the average defocus amount [DFe] obtained from the latest distance measurement result of <E> at that time.
After the distance measurement of <G>, which is performed at a timing of [0.8 seconds] after focusing, an interrupt is generated by opening the release switch (S2) at a timing of <1<□> in Fig. 14. For example, the average defocus amount [DFd] obtained from the distance measurement result of <D> is used to drive the mirror while it is up.

By doing this, even if you try to lock the AF, shake the camera, and wait for 0.8 seconds or more to perform the release operation that matches the photographer's intention, you can still take a photograph that is in focus.

FIG. 15 shows a schematic flow of a subroutine (LNS) for driving the lens during mirror up, which is called at <#450> of the main routine of FIG.

When this subroutine is called, first <#1500
In >, the card one-shot flag input in <#502> of FIG. 5 is determined, and if there is a card one-shot flag, the process proceeds to <#1538> without driving the mirror up. In <#1538>, the drive pulse counter [BCNT] for driving the lens is set to "0', and then returns to the main routine. Similarly, in <#1502>, (auxiliary light A
F mode), the process proceeds to <#1538> without driving the mirror up. ' This (auxiliary light AF mode) is switched according to the flow shown in FIG. The flow shown in FIG. 19 is <#514. > and <#516>, and this flow is passed when the determination in <#514> is that the object is out of focus.

In this flow, first, in <#1900>, it is determined whether the subject has low confidence, that is, the reliability of the focus detection result, and if it is low confidence, that is, if the reliability is low, then in <11902>. Determine whether the subject is dark. This judgment is performed by the focus detection circuit (
It is determined that it is dark when the gain of the amplifier circuit (AGC) of the AFS is twice. If this corresponds to the Apex digital signal [Bv], it becomes [-1]
corresponds to If it is determined in <#1902> that the subject is dark, the auxiliary light flag is set in <#1904> and then the process returns to the main routine (<#590>
). If it is determined in <#1902> that the subject is not dark, the process returns to the main routine without setting the auxiliary light flag (, <#590>).

Then, if this auxiliary light flag is set at the next distance measurement,
When integrating the step <#500>, the auxiliary optical circuit (AS
The auxiliary light is projected onto the subject from L).

Returning to Fig. 15 and continuing the explanation, next, <#1504
> to determine whether it is in (moving object mode). If it is not (moving object mode), then the AF lock flag is determined in <#1506>.

If the AF clock is on, as shown in Table 1, the process proceeds to <#153B> without driving during mirror up.

If the AF clock is not in progress, then it is determined in <#1508> whether continuous AF is being performed.

If it is determined to be continuous AF based on the determination of the continuous AF that exited from (moving object mode) or the continuous AF flag sent from the card circuit (CD), the process advances to <#1514> and the current Set the defocus amount [DF(current)] you have in the memory for driving during mirror up [DFm]. This defocus amount [D
F(now)] is the defocus amount at the time when focus was determined before entering this flow, and is not the average defocus amount.

If it is determined in <#1508> that continuous AF is not used, then in <#1510> it is determined whether the base defocus amount [DFo] is stored. If the base defocus amount [DFo] is not stored, the process also proceeds to <#1514>. An example of this is
Before focusing, press the metering switch (Sl) and release switch (
S2) are both closed (hereinafter referred to as release start before focusing), and the moving object determination routine of FIG. 8 is not passed, so the base defocus amount [DF,
]. In other words, even when the release starts before focusing, the defocus amount [DF'(
)] to drive the mirror up. Also, even during the moving object detection routine, if the initial average defocus amount cannot be calculated, similarly, <#15], 0> is determined.
Proceed to #1514>.

On the other hand, if an interruption due to closing of the release switch (S2) occurs during the moving object determination, the process proceeds to <#1512>. In <#1512>, the average defocus amount [D
F (flat)] is set in the mirror-up drive memory [DFm]. There are various embodiments of this step <#1512> depending on what kind of shooting situation the camera emphasizes, that is, the premise of the camera. Some examples are shown in FIGS. 16(a) to 16(e).

FIG. 16(a) shows the case of a camera that assumes a stationary subject, and the base defocus amount [OF,] is set in the drive memory [DFm]. Figure 16 (b) shows the case of a camera that assumes a moving subject, and the latest average defocus amount [DF4] is stored in the driving memory [DFml].
Set to .

Figure 16 (c) shows the case of a camera that is designed for portrait photography, and when [068 seconds] have elapsed since focus, <G
The focusing average defocus amount [D
Set the F pull in the drive memory [DFml. In addition,
When using this flow, <#870> and <
#875>, it is necessary to set the average defocus amount [DFG] after focusing by placing the flow shown in FIG. 20 between them.

In other words, if the second judgment counter [1] is "4", it means that there are four average defocus amounts [DFx], and it is determined that exactly [0.8 seconds] have passed since in-focus. Therefore, the flow is to set the average defocus amount [DF, ] at this point as the in-focus average defocus amount DFG].

FIG. 16(d) is a case where a versatile camera or a beginner's camera is used, and the time from focusing to the current timing, that is, the opening timing of the release switch (S2), is measured in <#1610>. ta] and <#1612
> determines whether this time [t3] is less than [1 second], and if it is less than [1 second], it is determined that the camera is not shaken, and <#1614> determines the latest average defocus amount. [
While setting the drive memory [DF,] to the drive memory [DFml,
[If it is longer than 1 second, it is determined that the camera is being shaken midway, and the base defocus amount [DF
, ] in the drive memory [DFml.

This is to prevent a change in defocus amount caused by shaking the camera with respect to a stationary subject from being mistaken for a movement of the subject.

In other words, if the object moves so slowly that it is not determined as a moving object in the moving object determination flow, the focusing accuracy will be better if the lens is driven using the latest average defocus amount. However, if the lens is driven using the latest average defocus amount, if the camera is gently swung toward a stationary subject, the AF lock will be determined as A.
Instead of being determined to be F-lock, the focus will be on a completely different area. In order to prevent such a situation, the value set in the drive memory [DFml] is changed depending on the time from when the camera is in focus until the release switch (S2) is closed.

Fig. 16 (E) is a modification of Fig. 16 (:), in which the average defocus amount [DFG] after focusing is stored to determine the time from in-focus to the occurrence of an interrupt due to closing of the release switch (S2). This is used as a substitute for determining whether or not the If the average defocus amount after focusing [DFG] is stored, it is assumed that more than [0.8 seconds] have passed after focusing.
1622>, the base defocus amount [DFO] is set in the drive memory [DFml], and if the average defocus amount after focus [DFG] is not stored, it is used for one-shot AF or for a moving subject. As focus compensation, the latest average defocus amount [:OF,] is set in the drive memory [DFml] in <#1620>.

By the way, these were all explained as different embodiments, but
All these flows are included in the microcomputer (μC) program, and the card circuit (CD) and memory IC (E
The above five flows (
By switching between (a) and (e) in FIG. 16, one camera can be set to different operating states.

For example, when assembling a camera, memory IC (E"FROM)
If you write "1" in the specified address of Figure 16 (a)
If "2" is written, the flow shown in FIG. 16 (b) may be selected. Similarly, when replacing an IC card, an I
If the C card is installed, the flow shown in Figure 16 (a) will be selected, and if the IC card labeled "2" is installed, the flow shown in Figure 16 (b) will be selected. good.

Returning to FIG. 15 and continuing the explanation, the drive memory [D
After any of the above average deformation force amounts are set in Fml, in <#1516> and <#1518>,
Using the lens drive amount data in the drive memory [DFm], a zone is determined as to whether mirror up drive is possible or not.
When the lens drive amount is [70μm≦DFm<200μm], in order to drive during mirror up, <#l520
＞Proceed to ＞.

If it is determined in <#1516> that the lens drive amount is less than [70 μm], the mirror-up drive is not performed and the process returns to the main routine. That is, this <#1516
It is thought that the subject that comes to the > step is often a stationary subject, and in this case, there is no need to drive the mirror up while it is within the in-focus zone. It also has the meaning of not making the feel worse when the mirror is up.

Also, in <#1518>, the lens drive amount is [200a m
] If it is determined that the above is the case, the mirror-up drive is not performed and the process returns to the main routine. In other words, if the subject is moving fast, use <#1540> or <#1.
514>, so only subjects with slow moving speed can be photographed.
#1518>, and the movement speed is slow, so the maximum amount of drive during mirror up is [200
This is because a value of less than [μm] is sufficient. Conversely, if the lens drive amount exceeds [200 μm], this is because there is a possibility that the camera was shaken but the AF was not locked.

On the other hand, when branching to <#1514>, since it is completely unclear whether the subject is a stationary object or a moving object, the process proceeds to <#1520> on the premise that the mirror is being driven while the mirror is up.

If it is determined in <11504> that the mode is (moving object mode), the process proceeds to <#1540>, and the current defocus amount [from the start of integration by the light receiving circuit (CCD) for DF (now) to the current In other words, the release switch (S
The time until the closing timing of 2) is measured and set as [t1]. <#1542) Add the mirror-up time lag [70m5] to this time [t1] and get [t2]
Then, multiply the moving object speed [V] calculated during (moving object mode) in <#1544> by this time [t2] to find the amount of focus deviation [ΔDF] due to the movement of the subject during the time lag from integration to exposure. (Hereinafter, since moving object correction is performed using this amount of focus deviation [ΔF], this amount of focus deviation [ΔDF] will be referred to as a moving object correction amount).

Subsequently, in <#1546>, the sign of the moving object speed [V] is determined. In this determination, if [V>0], it means that the defocus has increased in the direction of focus, and it is determined that the subject has approached the camera.

If it is determined that the subject is approaching the camera, <#1
550>, the moving object correction amount [ΔDF] is multiplied by a coefficient of [1/4] and added. The reason for this is that even if the subject approaches the camera at a constant speed, the amount of defocus on the image plane does not change at a constant speed, but is a reciprocal function of the speed, and if it is approximated by a straight line, there will be insufficient correction. This is to prevent this from happening. Therefore, as a correction coefficient [1+1/X]
think of. Considering the assumed moving speed of the subject, the above variable [X] is set as an experimental value of [3 to 5].
The results show that the range of .
), the variable [x] is set to [4], and the moving object correction amount [ΔDF] is multiplied by a coefficient of [1+1/4].

Conversely, if it is determined that the subject is moving away from the camera, <#
1548> and set the moving object correction amount [ΔDF] to [1-1/
Multiply by the coefficient of 4].

After that, in <#l552>, value correction is applied to the moving object correction amount [ΔDF] in consideration of the error in the setting conversion coefficient [K] between the defocus amount and the lens drive amount in the photographing lens. To specifically show this value correction, as shown in FIG. If the value [A/Vo] is larger than the predetermined aperture value [J1], that is, if the photographing lens is dark, the moving object correction amount [ΔDF] is multiplied by a factor of [1,2] in <#1802>, and further, When the value of the conversion coefficient [K] is small, the amount of lens movement per one count for lens driving is large, so the error of the conversion coefficient [K] is large (<#
1806>, the moving object correction amount [ΔDF] is multiplied by a coefficient of [1, 2], and the moving object correction amount is converted to the drive amount using a correction conversion coefficient that corrects the error of the setting conversion coefficient [K]. Make up for the lack of correction amount by making it the same.

After performing the K value correction, <#1554> adds the moving object correction amount [ΔDF] to the current defocus amount [DF (current)].
] is added and stored in the drive memory [DFm],
Proceed to <#1520>.

<#l524>, <#l518>, <#l55
In <#1520>, which proceed from 4>, the lens drive amount to be driven during mirror up, which is stored in the drive memory [DFm], is multiplied by the setting conversion coefficient [K] of the photographing lens, and the lens is adjusted. Set the drive pulse counter [ECNT] for driving. At <11522>, it is checked whether the value of the driving pulse counter [ECNT] is larger than "40", which is the maximum number of pulses that can be driven in a limited time during mirror up. “40”
If it is determined that the value is smaller than , the process proceeds to <#1536>, starts lens driving, and returns to the main routine.

On the other hand, at <11522>, the drive pulse counter [ECN
If the value of T] is determined to be “40” or more,
The lens is driven before starting exposure control, but the amount of drive is also limited. That is, <#
1524>, the value of the drive pulse counter [ECNT] is "7o", which is the maximum number of pulses for driving before release, and "4o", which is the maximum number of pulses for driving during mirror up.
Determine whether it is larger than 110"."110"
If it is determined that this is the case, the pre-release drive pulse counter [EECNT] is set to "70" in <#1528> in order to perform the pre-release drive for the maximum number of [70 pulses]. Also, <#1524> sets the drive pulse counter [
EC! ';T] is determined to be smaller than 711o'', the drive pulse counter [ECN
The value obtained by subtracting "4o" from the value of Tr is set in the pre-release drive counter [EECNT].

Next, at <#1530>, the pre-release lens drive is started, and at <#1532>, the pre-release drive pulse counter [
EECNT] waits until it becomes "θ". The maximum driving time of this pre-release lens driving is [approximately 40 m5], and the time lag does not increase significantly. <#1534
In >, the drive pulse counter [ECNT] is set to "4o" so that the remaining lens drive is performed while the mirror is up, and in <#1536>, lens drive is started and the process returns to the main routine.

After returning from the subroutine (LNS>>, the main routine calls the subroutine (exposure control) at <#455>. Figure 17 shows this subroutine (exposure control).
This shows the general flow of the process.

When this subroutine is called, first <#1724
> to start the mirror up, and <#1726> to start the aperture operation of the photographic lens. Then (moving body mode)
etc., the lens drive has started during mirror up, so the drive pulse counter [ECNT
] waits until the value becomes "o". Note that if the lens is not driven during mirror up, the drive pulse counter [ECNT] is initially set to "0", so <#1728> passes through immediately. And <#17
After completely stopping the photographic lens at <#173>
2>, wait until [70m5] has elapsed from the start of mirror up. That is, the mirror-up and aperture operation end at [70 m5]. When the mirror up, lens drive during mirror up, and aperture operation are all completed, the exposure operation starts from <#1734>. <#
1734> to run the first curtain of the shirt curtain, and <#173
At step 6>, the process waits for the exposure time determined by the calculation at step <#430> of the main routine, and at step <#1738>, the rear curtain of the shutter is run to complete the exposure. Then, return to the main routine.

The sea fence of camera operations has been explained above, and the microcomputer (μC) that performs these operations uses the detection deviation by the focus detection means and the setting conversion coefficient to determine the drive amount for focus adjustment (in this example, (drive amount for motion compensation)
The microcomputer (μC) converts the setting conversion coefficient [K
] Conversion control means is configured to operate the conversion means using a corrected conversion coefficient that corrects the error.

[Another example]

Other embodiments other than those described in the previous embodiments will be listed below.

<i> The reference values for various determinations that have been made to determine the subject's ° state and the photographer's intentions can be changed arbitrarily.

2> If the subject is judged to be dark, if the shooting magnification is judged to be high, or if the subject is slow and moving away from the camera, it is necessary to prevent the mirror from moving while the mirror is up. It is not necessary to set the focus adjustment state, but it may be a moving object focus adjustment state that allows driving while the mirror is up.

<3> In the previous embodiment, if it is determined that the subject is moving at a high speed, the drive amount correction during mirror-up driving may be omitted.

<4> In the previous embodiment, the photographic lens is configured to be detachable from the camera body, and lens information specific to the photographic lens is input from the lens circuit (LEC) attached to the photographic lens. Although a camera configured to do so has been described, the present invention can alternatively be applied to a camera in which a photographic lens is provided in a fixed state.

<5> In the previous embodiment, a configuration in which three focus detection areas were provided was described, but instead, a plurality of other focus detection areas may be provided (or, the focus detection area may be Only one may be provided.

〔Effect of the invention〕

As described above, after the start of the release operation, the camera according to the present invention calculates the drive amount for focus adjustment using a correction conversion coefficient that corrects errors in the setting conversion coefficient, and performs focus adjustment based on the drive amount. By using this method, it is possible to perform focus adjustment while using the detected deviation just before the mirror is raised, with less insufficient focus adjustment amount, and it is possible to perform focus adjustment until just before exposure, allowing good tracking of a moving subject. It has now become possible to provide a camera that can take advantage of photo opportunities, and as a whole can take photos with good focus accuracy at the desired timing.

[Brief explanation of the drawing]

The drawings show an embodiment of the camera according to the present invention, in which Fig. 1 is a circuit block diagram, Fig. 2 is a perspective view of the periphery of the focus detection optical system, Fig. 3 is a field view of the finder, and Figs. Figure 5・
Figures 7 to 9, Figure 15, Figures 16 (a) to (e), and Figures 17 to 21 are flowcharts showing camera operations, and Figures 6 (a) and (b) are focus A schematic diagram showing the sea fence of the detection operation, Figures 1O (a) to c) are schematic diagrams showing the relationship between the movement of the subject and the camera operation, and Figures 11 to 14 are time charts of the focus adjustment operation, respectively. It is. (TL)...Photography lens.

Claims (1)

[Scope of Claims] 1. Focus detection means for repeatedly detecting the deviation from the in-focus position of the photographing lens with respect to the subject, and a drive amount for focus adjustment using the detected deviation by the focus detection means and a setting conversion coefficient. and a focus adjustment means for moving the photographing lens toward the in-focus position by the drive amount until the shutter starts operating, after the release operation starts, the setting conversion coefficient is changed. A camera further comprising a conversion control means for operating the conversion means using a corrected conversion coefficient that corrects an error. 2. The setting conversion coefficient is set so that the driving amount is set to a value that does not cause the photographing lens to be driven beyond the in-focus position, taking into account an error thereof, and the correction conversion coefficient is The camera according to claim 1, wherein the setting conversion coefficient is increased. 3. The camera according to claim 2, wherein the conversion control means operates the conversion means using the corrected conversion coefficient when the set conversion coefficient is smaller than a predetermined value. 4. The camera according to claim 2, wherein the conversion control means operates the conversion means using the correction conversion coefficient when the open aperture value of the photographic lens is larger than a predetermined aperture value.